How Science Works

One aspect of modern science that contributes to the cult of the expert is the assumption that science depends on complex technology, so it is hopeless for someone without technical training to try to understand the details of the scientific process. It is certainly true that scientists working today have amazing pieces of equipment that make it possible to do things that the previous generation could only dream about and the one before couldn't even imagine. For example, the Human Genome Project, in which the entire genetic code of human beings was determined, would not have been possible without the development of automated sequencing machines for reading the information in long strands of DNA. The human genetic code consists of about 30,000 genes distributed among 24 different chromosomes. The letters of this code are the four nucleotide bases of DNA, and each gene consists of a unique sequence of these bases. In humans, the total number of nucleotide bases on the 24 chromosomes is about 3 billion. Two groups published first drafts of the human genetic code in February 2001: a private company called Celera Ge-nomics and a public consort ium of scient ists from various universities and government agencies. The private company used 300 DNA sequencers, which cost $300,000 each, plus powerful supercomputers to analyze the data from the sequencers to produce their draft of the human genome in fewer than 3 years (Pennisi 2001; Lorentz et al. 2002).2

This example could be multiplied many times, but there are still opportunities to make discoveries the old-fashioned way, by using simple observations. To be sure, this traditional approach depends on hard work , perseverance, detailed k nowledge to provide a context for interpreting new observations, and sometimes good luck. For example, Philip Gingerich, Hans Thewissen, and others found a series of fossils in Pakistan and Egypt during the last 30 years that clearly established how whales evolved from even-toed ungulates, the group of mammals that includes cows, sheep, hippos, and related species (Thewissen 1998; Sutera 2000; Wong 2002). Their research involved field-work under ver y challenging conditions, both env ironmental and political; painstaking preparation of the fossils; then v isual comparison of the various specimens. The sequence of intermediate forms between terrestrial mammals adapted for running and marine mammals w ith no external limbs, nostrils on the tops of their sk ulls, and other adaptations for living in water is a truly amazing illustration of an important evolut ionary transformat ion, yet demonstration of this transformation was primarily a low-tech effort.3

These apparently very different stories about deducing the genet ic code of humans and describing the evolut ionary transformation from ungulates to whales have some common feat ures despite their different reliance on complex technology. These common feat ures are mainly ways of thinking about problems, that is, mental tools rather than technological tools. These mental tools are fundamental component s of the scient ific process, which make science an especially productive way of solv ing problems. I believe that this aspect of how science works is accessible to anyone willing to exercise his or her brain, regardless of technical background. Therefore, I use examples that illustrate some of the basic analytical methods that underlie all areas of science, rather than examples that show the contribution of gee-whiz technology.

A bit more consideration of the Human Genome Project may help clarify this point. Although decoding enormous quantities of DNA required the development of automated machines and computers capable of analyzing large amounts of data, it also depended on thorough understanding of the structure of DNA and clever experiments to tease apart how DNA molecules are synthesized. The design of these experiment s was no different in principle than the design of any experiments in biology and medicine, even ones in which result s could be obtained by simple observation of experimental subjects, such as human volunteers in medical experiment s. Designing critical experiment s to discriminate clearly among alternat ive hypotheses is essen tially the same process whether the hypotheses are about effects of vitamin C on colds (Chapter 2) or about the structure of molecules such as DNA, although experiments on the latter may require highly specialized equipment for obtaining and analyzing results. By telling some scientific stories that don't involve complex technology, I hope to give you some tools for understanding the scient ific process that can be applied much more broadly to additional examples, including those in which technology plays a larger role.